What video formats and codecs does FFmpeg support? How to choose the appropriate format? - 面试题

FFmpeg supports numerous video formats and codecs. Understanding their characteristics is crucial for choosing the appropriate encoding scheme.

Common Video Container Formats

MP4 (MPEG-4 Part 14)

Features:

Excellent compatibility, supported by almost all devices
Supports multiple codecs (H.264, H.265, AAC, etc.)
Suitable for network transmission and storage

Use Cases: Web video, mobile devices, social media

bash
# Create standard MP4
ffmpeg -i input.avi -c:v libx264 -c:a aac output.mp4

# Create fast-start MP4
ffmpeg -i input.mp4 -c:v libx264 -c:a aac -movflags +faststart output.mp4

MKV (Matroska)

Features:

Open source format, powerful features
Supports almost all codecs
Supports multiple audio tracks and subtitle tracks
Suitable for storage and collection

Use Cases: HD video storage, multi-language videos

bash
# Create MKV
ffmpeg -i input.mp4 -c:v libx264 -c:a aac output.mkv

# Preserve all tracks
ffmpeg -i input.mp4 -c copy output.mkv

AVI (Audio Video Interleave)

Features:

Legacy format, good compatibility
Relatively simple features
Does not support modern codecs

Use Cases: Legacy device compatibility

bash
# Create AVI
ffmpeg -i input.mp4 -c:v mpeg4 -c:a mp3 output.avi

WebM

Features:

Open source format developed by Google
Optimized for web
Supports VP8, VP9, AV1 codecs
Small file size, good quality

Use Cases: Web video, HTML5 video

bash
# Create WebM
ffmpeg -i input.mp4 -c:v libvpx -c:a libvorbis output.webm

# Use VP9 encoding
ffmpeg -i input.mp4 -c:v libvpx-vp9 -c:a libopus output.webm

MOV

Features:

Format developed by Apple
Supports professional codecs like ProRes
Suitable for professional video production

Use Cases: Professional video production, Apple devices

bash
# Create MOV
ffmpeg -i input.mp4 -c:v libx264 -c:a aac output.mov

# Use ProRes encoding
ffmpeg -i input.mp4 -c:v prores_ks -profile:v 3 output.mov

Common Video Codecs

H.264 (AVC)

Features:

Most widely used video encoding standard
Excellent compatibility
Medium compression efficiency
Fast encoding speed

Use Cases: General video, web video, mobile devices

bash
# H.264 encoding
ffmpeg -i input.mp4 -c:v libx264 -crf 23 output.mp4

# High quality H.264
ffmpeg -i input.mp4 -c:v libx264 -crf 18 -preset slow output.mp4

# Fast H.264
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset ultrafast output.mp4

H.265 (HEVC)

Features:

Successor to H.264
50% higher compression efficiency than H.264
Slower encoding speed
Compatibility is improving

Use Cases: 4K/8K video, high compression requirements

bash
# H.265 encoding
ffmpeg -i input.mp4 -c:v libx265 -crf 28 output.mp4

# High quality H.265
ffmpeg -i input.mp4 -c:v libx265 -crf 23 -preset slow output.mp4

VP9

Features:

Open source codec developed by Google
Compression efficiency close to H.265
Completely free
Suitable for web video

Use Cases: Web video, YouTube

bash
# VP9 encoding
ffmpeg -i input.mp4 -c:v libvpx-vp9 -crf 30 -b:v 0 output.webm

# High quality VP9
ffmpeg -i input.mp4 -c:v libvpx-vp9 -crf 18 -b:v 0 output.webm

AV1

Features:

Next-generation open source codec
30% higher compression efficiency than H.265
Slow encoding speed
Limited compatibility

Use Cases: Future video, high quality compression

bash
# AV1 encoding
ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -strict experimental output.webm

ProRes

Features:

Professional codec developed by Apple
Visually lossless compression
Larger file size
Suitable for post-production

Use Cases: Professional video production, post-production

bash
# ProRes encoding
ffmpeg -i input.mp4 -c:v prores_ks -profile:v 3 output.mov

# ProRes 422
ffmpeg -i input.mp4 -c:v prores_ks -profile:v 1 output.mov

Audio Codecs

AAC

Features:

Most widely used audio encoding
Excellent compatibility
Good quality, small file size
Supports multi-channel

Use Cases: General audio, web audio

bash
# AAC encoding
ffmpeg -i input.wav -c:a aac -b:a 128k output.aac

# High quality AAC
ffmpeg -i input.wav -c:a aac -b:a 256k output.aac

MP3

Features:

Most popular audio format
Excellent compatibility
Lossy compression
Suitable for music

Use Cases: Music, portable devices

bash
# MP3 encoding
ffmpeg -i input.wav -c:a libmp3lame -b:a 192k output.mp3

# High quality MP3
ffmpeg -i input.wav -c:a libmp3lame -b:a 320k output.mp3

Opus

Features:

Open source audio codec
Excellent quality, low latency
Suitable for speech and music
Small file size

Use Cases: Web audio, voice calls

bash
# Opus encoding
ffmpeg -i input.wav -c:a libopus -b:a 128k output.opus

# High quality Opus
ffmpeg -i input.wav -c:a libopus -b:a 256k output.opus

FLAC

Features:

Lossless audio compression
Quality same as original file
Smaller file than WAV
Suitable for music collection

Use Cases: Music collection, lossless audio

bash
# FLAC encoding
ffmpeg -i input.wav -c:a flac output.flac

Format Selection Guide

Choose Based on Use Case

Scenario	Recommended Format	Recommended Codec
Web video	MP4	H.264 + AAC
HD storage	MKV	H.265 + AAC
Web video	WebM	VP9 + Opus
Professional production	MOV	ProRes
Music storage	FLAC	FLAC
Mobile devices	MP4	H.264 + AAC

Choose Based on Quality Requirements

High Quality:

bash
ffmpeg -i input.mp4 -c:v libx264 -crf 18 -preset slow -c:a aac -b:a 256k output.mp4

Medium Quality:

bash
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4

Low Quality (Small File):

bash
ffmpeg -i input.mp4 -c:v libx264 -crf 28 -preset fast -c:a aac -b:a 96k output.mp4

Format Conversion

Format Interconversion

bash
# MP4 to MKV
ffmpeg -i input.mp4 -c copy output.mkv

# AVI to MP4
ffmpeg -i input.avi -c:v libx264 -c:a aac output.mp4

# WebM to MP4
ffmpeg -i input.webm -c:v libx264 -c:a aac output.mp4

Codec Conversion

bash
# H.264 to H.265
ffmpeg -i input.mp4 -c:v libx265 -crf 28 output.mp4

# VP9 to H.264
ffmpeg -i input.webm -c:v libx264 -crf 23 output.mp4

Choosing the appropriate format and codec requires considering multiple factors such as compatibility, quality, file size, and encoding speed.